Field
The invention relates to a method and system for generating and shading a computer graphics image in a tile based computer graphics system.
Related Art
Tile based rendering is a technique for rendering 2D or 3D computer graphics images. An image is sub-divided into a plurality of blocks or tiles, which are typically rectangular, and each comprises a plurality of image pixels.
Primitive data representing geometrical objects is read from memory and transformed into screen space. Primitives are often polygons but may be lines or points. An object list is then created, for each tile, indicating the primitives, if any, which are located either partially or wholly within that tile.
Each tile is rendered independently. For each tile, the primitives identified in the respective object list are processed and hidden surface removal may be performed. The resultant pixel data for visible objects is then passed to a shading unit which applies textures and shading to each pixel within a visible object. After final pixel values have been determined for each pixel in the tile, the pixel data for the tile is written to memory for display on an output device.
For a triangle primitive the primitive data will typically comprise data defining the vertices and the surface they define, with a flag indicating relevant shading and texture data to be applied.